160 



ROUNDWORMS— THE NEMATHELMINTHES 



Esophagus 



Trachea 



Lung 



Inferior 

 vena cava 



Heart 



r Human feces 



Stomach 



Small intestine 

 (larvae grow to 

 adults and live 

 here) 



Femoral vein 



Migrating 



larvae 

 (enlarged) 



Fig. 11.5. Diagram illustrating method of hookworm infection. The eggs hatch in 

 human feces passed from an infected person. The newly hatched larvae migrate in all 

 directions. They then bore their way into the blood stream of any person that contacts 

 them with the bare skin. They go through the veins to the heart, thence to the lungs, 

 and are coughed up into the throat. They may be swallowed back down the esophagus, 

 to the stomach, and finally to the small intestine where they grow into adults and live 



the rest of their lives. 



